Why is most content on Lemmy just old memes?

Because the people who left reddit for lemmy are the people who left digg for reddit, mostly. So old Internet people. Hence old memes.
Edit: my phone decided digg should be high. IDK.
- I was on reddit before I was on digg, but yeah. My migration was reddit > digg > reddit > lemmy
- I'll take some recycled old memes over the groupthink spam reddit has become. If I never see another buy GME apes strong post again I'll die happy.

I find it quite funny that you sometimes see posts here that say that they are glad that all the smart people left reddit and the cringe people are now all on reddit.
All followed by the most cringe boomer humor i have ever seen. Like some shit that wouldn't even get upvoted on /r/funny

Don’t subscribe to those communities?
- Or post new content. I see lots of posts about people removed that there isn't enough content they like, but few of them posting any content.
- Yeah, I don't see this at all, maybe I subscribe to very different communities.
- Or block them if you’re browsing all

Because you subscribe to communities that are full of old memes and/or because you browse 'all' instead of your subscribed feed.
As to why the wider Lemmyverse has too much of that sort of stuff, it's because a lot of people are trying to recreate Reddit instead of building something new. Or because they're trying to kickstart the something new by posting plenty of content and, inevitably, much of it is old.
Post stuff you want to see. Engage with stuff you want to see.

Some people who like to post memes also like to post them in multiple communities, and crossposting can be much more obvious here than on reddit

I mean, it's the low hanging fruit content. It gets done engagement, some amount of almost nostalgia, but doesn't require much work to post. It's not the end of the world, it just comes in larger volumes and takes up quite a bit of "all". Honestly blocking some of those communities would probably work well to clean up your all feed if you wanted.

We’re kind of at the tail end of a nostalgic meme trend. !antiquememesroadshow@lemmy.world blew up about 3 weeks ago, it spread to the other meme communities, and everyone was having fun with posting crusty old memes.

Unsubscribe from the meme communities. Problem solved.
- Or block it so it won't appear under "all".
  
  It's a total pain to have to go into the community, scroll all the way down, and then get an error message when you click the block icon. Or a login screen. It should be possible to block communities from the front page.

If I could mandate one rule for the fediverse that it didn't already have, it would be a hard ban on reposts, especially those undated Twitter screencaps that took over entire subreddits the last few years.

Probably because the average lemmings is way older than the average redditor.
- It's possible, is there any actual data published on age distribution?
  
  Great question, I don't think so. I just feel like that I rarely see teens here, or maybe even my age group is uncommon too to some degree. (22 here)

It’s because a lot of people here are people who miss the earlier days of the internet and are trying to recreate that feeling. I’m not that old but it’s got me feeling nostalgic so I enjoy it
- The early days of the internet was waiting for 20 minutes for a naked picture of Pamela Anderson to finish loading on the screen. I'm not sure if anyone really wants to recreate that.
  
  You’ve gone back too far! I meant mid to late aughts (2005-2010)

Yeah, I need to move off of all and start curating a subscription list. Before hexbear was federated there wasn't any need.

It's a way to add content and (hopefully) build interest in the system. It's also a way for Lemmy users to show they are just a little different.

You can block the meme communities, then you won't see those posts in your feed.
I sort of enjoy seeing the ones I had forgotten about.

I only use the subscriptions feed, so I only see what I want to see and that removes this problem.